Turbine engine blades, and particularly those used for aircraft, must be machined to precise airfoil contour, with perfect control of thickness. Chucking to machine to the necessary thinness is difficult, the blade blanks being likely to deflect severely under forces of machining. The present general practice appears to be to machine the blades oversize, and then hand file them to fit the contour of templates.
Meltable matrix chucking in which an entire blade surface may be held embedded in a low melting point metal matrix, is known from my U.S. Pat. No. 3,790,152. This chucking method avoids deflection under machining forces. The fixture there shown proved to be satisfactory for relatively small blades. However, in order to handle larger blade blanks, and transfer them from one chuck to another in mass production, the folding fixture there shown was not adequate.
Further, chuck improvements were necessary to speed the meltable matrix process and adapt it to blades which were more highly twisted. Finally, to achieve faster production, entirely new machining and inspection equipment was necessary to finish the blades in essentially a two-stage operation described hereafter.